A general treatment of traction PWM converters for load flow and harmonic penetration studies

This paper presents a general treatment in the frequency domain of PWM controlled line-side converters in traction applications. The model is described by means of powerful analytical expressions which take into account the operating point of such devices as single phase PQ loads. Special attention is paid to define general structures where the number of pulses and the number of interlaced PWM converters of each locomotive can take any value. The harmonic emission of each locomotive is represented by a harmonic voltage source coherent with the selected operating point. Several locomotives acting simultaneously at the same busbar are also considered. This model does not require iterative harmonic analysis, therefore its implementation in conventional software is straightforward. Load flow calculations and harmonic propagation studies have been performed using this model in a network with more than 900 busbars and 6 traction substations.